1. Field of the Invention
The present invention relates to a tracking apparatus which is applied to a player for playing an optical disc having a recording format for a sampled servo system, and more particularly to a tracking apparatus which has a one-track jump function.
2. Description of the Related Art
When a conventional tracking apparatus jumps one track on a disc, a tracking servo loop is first opened, and a kick pulse is applied to a driving circuit of a tracking actuator. In response, an information reading position, which is the position irradiated by a light beam spot emitted from a pickup to the disc, is moved in a radial direction of the disc. Thereafter, when a zero-cross point of a tracking error signal is detected, the generation of the kick pulse is stopped, and a brake pulse is instead generated to return the tracking servo loop to a closed state. A one-track jump control as described above is disclosed, for example, in Japanese Patent Publication No. 3-3289.
In a track jump operation performed by a conventional tracking apparatus, a zero-cross point of the tracking error signal changes if the track pitch of a disc is variable, and the pulse width of the kick pulse also varies correspondingly. However, since the pulse width of the brake pulse is usually constant, a maximum value of the jump speed may become too high when the pulse width of the kick pulse is larger than normal. Thus, when the jump operation is switched back to a tracking servo operation, an emitted spot is not smoothly led into an adjacent target track, thus causing an unstable tracking operation.